Abstract
The growth of thiamine-requiring microorganisms such as L. fermenti 36 and Kl. apiculata was inhibited by imidazolethiamine (1-[(2-methyl-4-amino-5-pyrimidinyl)-methyl]-4-(2-hydroxyethyl)-5-methylimidazole) (I), while the growth of both L. casei and L. arabinosus which require no thiamine wasn't inhibited by I. The inhibitory effect of imidazolethiamine was competitive and reversed only by thiamine ; the inhibition index for L. fermenti was 300 and that for Kl. apiculata was 7,000. Imidazolethiamine also proved to have the inhibitory effect on Sacch. carlsbergensis 4228,on which thiamine and the compounds reversible to thiamine were shown to be inhibitory.
